A multi-scale crystal plasticity model for cyclic plasticity and low-cycle fatigue in a precipitate-strengthened steel at elevated temperature. (2017)

• Record Type: Journal Article
• Authors: Li, Dong-Feng; Barrett, Richard A.; O'Donoghue, Padraic E.; O'Dowd, Noel P.; Leen, Sean B.
• Is Part Of: Journal of the mechanics and physics of solids. Volume 101(2017:Apr.)
• Page Start: 44
• Page End: 62
• Publication Date: 2017
• Subjects: Tempered martensite ferritic steels -- Strain gradient-based crystal plasticity -- Cyclic softening fatigue -- Finite element -- Crack initiation; Mechanics, Applied -- Periodicals; Solids -- Periodicals; Mechanics -- Periodicals; Mécanique appliquée -- Périodiques; Solides -- Périodiques; Mechanics, Applied; Solids; Periodicals; 531.05
• DOI: 10.1016/j.jmps.2016.12.010
• Languages: English
• ISSNs: 0022-5096

Abstract

Abstract: In this paper, a multi-scale crystal plasticity model is presented for cyclic plasticity and low-cycle fatigue in a tempered martensite ferritic steel at elevated temperature. The model explicitly represents the geometry of grains, sub-grains and precipitates in the material, with strain gradient effects and kinematic hardening included in the crystal plasticity formulation. With the multiscale model, the cyclic behaviour at the sub-grain level is predicted with the effect of lath and precipitate sizes examined. A crystallographic, accumulated slip (strain) parameter, modulated by triaxiality, is implemented at the micro-scale, to predict crack initiation in precipitate-strengthened laths. The predicted numbers of cycles to crack initiation agree well with experimental data. A strong dependence on the precipitate size is demonstrated, indicating a detrimental effect of coarsening of precipitates on fatigue at elevated temperature. Abstract : Highlights: Multi-scale strain-gradient micromechanical modelling of cyclic plasticity and fatigue for P91 steel. EBSD measured microstructures represented in meso-scale finite element model. Lath-precipitate unit cell represented in micro-scale model. Calibration and validation against measured cyclic stress-strain evolution and fatigue crack initiation. Predicted detrimental effect of M23 C6 precipitate coarsening on cyclic strength and fatigue resistance.